Muscle PhysiologyMuscle PhysiologyMuscle Physiology

Muscle FiberStructure

Muscle FiberMuscle FiberStructureStructure

Release of Ca++

from SarcoplasmicReticulum

Release of CaRelease of Ca++++

from from SarcoplasmicSarcoplasmicReticulumReticulum

MyofibrilMyofibrilMyofibril

Muscle Contraction

Muscle Muscle ContractionContraction

Z membrane(end of sarcomere)

Cross-bridgeBinding Site(need Ca2+)

Thick Filament (myosin)

Thin Filament (actin)

Sliding-Filament Model of Muscle

Contraction

SlidingSliding--Filament Filament Model of Muscle Model of Muscle

ContractionContraction

Muscle SpindleMuscle SpindleMuscle Spindle

Myotatic ReflexMyotaticMyotatic ReflexReflex

Knee-Jerk Reflex

KneeKnee--Jerk Jerk ReflexReflex

Alpha and Gamma Motor

Neurons

Alpha and Alpha and Gamma Motor Gamma Motor

NeuronsNeurons

Gamma Motor Neuron FunctionGamma Motor Gamma Motor

Neuron FunctionNeuron Function

Golgi Tendon Organ

GolgiGolgi Tendon Tendon OrganOrgan

Organization of Muscle ProprioceptorsOrganization of Muscle Organization of Muscle ProprioceptorsProprioceptors

Circuitry of the Reverse Myotatic ReflexCircuitry of the Reverse Circuitry of the Reverse MyotaticMyotatic ReflexReflex

Reciprocal Inhibition of Extensors and FlexorsReciprocal Inhibition of Extensors and FlexorsReciprocal Inhibition of Extensors and Flexors

Circuitry of the Polysynaptic Flexor Reflex

Circuitry of the Circuitry of the Polysynaptic Polysynaptic Flexor ReflexFlexor Reflex

Circuitry of the Crossed-Extensor

Reflex

Circuitry of the Circuitry of the CrossedCrossed--Extensor Extensor

ReflexReflex

Review of AnatomyReview of AnatomyReview of Anatomy

Whole MuscleWhole Muscle

Muscle fiber (cell)Muscle fiber (cell)

MyofibrilMyofibril

SarcomereSarcomere

MyofilamentsMyofilamentsMyosin Myosin

Actin Actin

CrossCross--bridging & bridging & ““ratchetingratcheting””

Twitch Rate Slow FastGlycogen Content Low HighGlycolytic Capacity Low HighFatigue Resistance High LowRespiration Type Aerobic AnaerobicCapillary Supply High Low

Slow- & Fast-Twitch MusclesSlowSlow-- & Fast& Fast--Twitch MusclesTwitch Muscles

Slow-twitch found more in muscles (like postural muscles)that must sustain contractions for long times without fatigue.Depend relatively more on fats for energy.

Atrophied FiberControl Fiber

Force (% of Peak Force)

Pow

er (u

n x

ft/s

)